I think this comment was correct. If you look at the video that was playing all day on FOX and look carefully at the very beginning (when the shuttle looked like a large, diamond-shaped thing because of the lens distortion), there is clearly something flying at the same speed as the shuttle below it and to the right. This is before any of the debris contrails appear, so it is likely that something large broke off very early on.
I also suspect that communication and data were cut off to the ground at least several seconds before those video clips were recorded.
I also suspect that communication and data were cut off to the ground at least several seconds before those video clips were recorded. Try 3 minutes for any video captured in the Dallas area ...
(20 seconds from horizon to horizon - YOU do the math.)